Answer: A) Cash flow diagram:
```
Year 0: - $4,500,000 (Payment 1)
Year 1: $2,600,000 - $500,000 = $2,100,000
Year 2: -$4,500,000 - $500,000 = -$5,000,000
Year 3: $2,100,000 - $500,000 = $1,600,000
Year 4: -$4,500,000 - $500,000 = -$5,000,000
Year 5: $2,100,000 - $500,000 + $4,500,000 = $6,100,000
```
B) Benefit/cost ratio:
```
Benefit = $2,600,000
Cost = $27,000,000 + 5*$500,000 = $29,500,000
PV of benefits = $2,600,000/(1+0.05)^1 + $2,100,000/(1+0.05)^3 + $1,600,000/(1+0.05)^5 + $6,100,000/(1+0.05)^5
= $2,314,553.54
PV of costs = $4,500,000 + $4,500,000/(1+0.05)^2 + $4,500,000/(1+0.05)^3 + $4,500,000/(1+0.05)^4 + $4,500,000/(1+0.05)^5 + $500,000*(1-(1/((1+0.05)^5/0.05)))
= $24,645,699.67
Benefit/cost ratio = PV of benefits / PV of costs = $2,314,553.54 / $24,645,699.67 = 0.094
```
The benefit/cost ratio of this project is less than one, which indicates that the project is not economically feasible. The cost of the project exceeds the present value of its benefits.
C) If the feasibility assessment period is changed to 50 years after construction, the present value of benefits will increase and the project may become more feasible. However, the cost of the project will remain the same. A new analysis would need to be done to determine the new benefit/cost ratio.